The ticket system is great for tracking the details. Until I started with Spiceworks I kept extremely detailed notes of everything I did everyday at the office. Now I simply create lots of tickets and it will serve as a sort of knowledge base for anyone who comes after me in this position.

I used to use PhatNotes on my Pocket PC then switched to Evernote Portable when I quit using the Pocket PC/Smartphone platforms. Both worked great but I had to export the notes into different formats (or print them) for others to benefit from the information stored therein.